Field of the Invention
The invention relates to an image apparatus and a lens, and particularly relates to a projection apparatus and a projection lens.
Description of Related Art
Along with development of science technology, image apparatus such as projection apparatus, digital video camera (DVC) and digital camera (DC) are widely used. One of core elements of the image apparatus is a zoom lens. Taking the projection apparatus as an example, during a zooming process, a distance between lens groups in the projection lens is adjusted and/or a distance between an image source (for example, a light valve) and a lens group closest to the image source is adjusted, so as to clearly project an image to a screen. However, when the distance between the image source and the lens group closest to the image source is changed (for example, enlarged), the lens group closest to the image source cannot completely cover an image beam coming from the image source, such that a part of the image beam is propagated to other element(s) outside the lens group, and such element(s) may absorb the energy of the image beam to cause a problem of overheating of the element(s).
The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art.